Process for producing alkenyl esters of endoalkylene-tetrahydrophthalic acids



Patented Jan. 9, 1951 .esrans or iIiNDQALKYLENE-TETRA- 'HYDBOPHZEHALIC ACIDS orrrce o super 0. Morris, Berkeley, Alva v. Snider, Richmond, and Robert M. Horowitz, Berkeley, Calif.,

-FI-his invention relates to a process for the prord-nctionbf polymeriz'ableunsaturated esters, and -lit more. particularly relates to a process for the production of alkenyl 'esters of endoalk'ylenefl gtetrahydrophthalic acids Still more particular.- zly; theinvention relates to a process for producing *betagamma-alkenm esters of 3,6cendoalkylene- 1,2,3,6-tetrahydrophthalic acids.

r The endoa1kyle'ne-l,2,3;fi tetrahydrophthalic acid esters have the general formula OH no lgouoooe Hg 'QHOOOR Whereinat least one B represents an allyl-typ unsaturated group which may b derived from an .l ns'aturated alcohol, as is,mo,re fully disclosed ,hereinbelow, and Y is analkylene groupsuch as a methylene grouper an ethylene. group. These compounds mayalso be named the allyl-type es.- ters of the 3,6-..endoalky1ene-M-tetrahydrophchal- .Yic, s. he all'ylyne st rs of the 3,6-endo alkylene L cyclohexen 1,2 dicarboxylic acids. There may. also be substituted upon the carbon atoms of the cyclohexene nucleus substituent groups such-as alkyl groups, halogen atoms, ether groups, etc. Suitable-alley groups which may be thus substituted upon'a nuclear carbon atom are the methyl, ethyl, n-propyl, i-propyl, n-butyly.

sec-butyl, i-butyl, tert-butyl, amyl, tert-amyl, hexyl, heptyl, and octyl group and the, like.

"-As" stated, at least one R in the general for.-

mula given hereinabove represents an allyl-type unsaturated group-which may be derived from an allylrtype alcohol, i. e. an alcohol which has a double bond of aliphatic character between two carbon atoms, one of which is directly attached -toa saturatedcarbinol atom. Such alcohols have 'fan; atomic'g'rouping which may bee-represented by the general formula y Examples of such allyl-type groups are the allyl, methallyl, ethallyl, chloroallyl, bromoallyl, methoxyallyl, ethoxyallyl, cyanoallyl, hydroxyallyl, crotyl, tiglyl, cinnamyl, methyl vinyl carbinyl, ethyl vinyl carbinyl, n-propyl vinyl carbinyl, isopropyl vinyl carbinyl, dimethyl vinyl carbinyl, methyl ethyl vinyl carbinyl, etc.

The other R group in the above general ior mula may also be an allyl-type group, for example, an ally! group of the type set forth in the above examples. It may also be any other type of v assignors to Shell v l pmen Company, an

Franoisoo -flalii a c rporation of D laware NoDrawin g Application September 30, 1944,

I Serial N0. 556,666;

unsaturated group such as vi yl yp g up as for example vinyl; isopr p n l, iso uteny-L orclohexenyl, veto, or an acetylenic group such as the pr p rgyl r up, The second R in t e said formula may also be a saturated hydrocarbon r un Thus, itm yn alkyl group such a a methyl, ethyl, -p pyl, i-pr p-yl, n bu-tyl, se buGyL i-butyl, amy-L hexyl, hePtyl,,-0r octylgroup. It may also be a group of cyclo-aliphatic character, e. g, a cyclopentyl, methylcyclopentyl,cyclohexyl, or methylcyclohexyl group, or an aromatic group, e. g. a. phenyl, tolY-Lor xylyl group. Any of the af r menti ned hy carbon groups may be substituted with suitable substituent atoms or groups, e. g. a halogen atom, Such as a chlorine or b omine, atom, a hyd xy groupi an lkoxy gro p,

e. ea m t o r roup, a keto r up, a cy i group, an aminogroup, etc,

In accordanoewith the process ,of the invention, a betagamma alkenyl ester'of a-lxfi-(ihdoalkylene-1,2, 3,6-tetrahydrophthalic acid having 1 to 2, carbon atoms in the endoalkylene group is p pared direct y y a reaction between a cyclic conjugated cliene having 5 too carbon atoms per molecule and a betagammwalkenyl ester of maleic acid having not more than l; carbon atomsin th tal amma-alk nylgroup. Thus, dictum- ,6- endome y -1 231 etrahydrophthalate ay be prepared by the simple condensation of cyclo pentadiene with diallyl maleate;

beta,gamma-alkenyl ester of maleic acid at a temi perature which is sufficiently elevated to effect the addition of the maleic acid ester to the conjugated cyclic diene, thereby forming the desired 3,6- endoalkylene-l,2,3,6-tetrahydrophthalic acid y ester. The reaction may usually be carried out, for example, by forming a mixture of cyclic conjugated diene and an unsaturated ester of maleic acid, heating the said mixture at a reaction temperature, e. g. a reaction temperature of between about 75 C. and about 125 (1., preferably about 100 C., and separating the unsaturated ester product by any suitable method, as by fractional distillation of the reaction product under diminished pressure. This condensation reaction may be carried out at atmospheric or superatmospheric pressures and in the presence or absence of a suitable solvent such as benzene or toluene.

Suitable cyclic conjugated dienes that can be employed according to the process of the invention include cyclopentadiene, methylcyclopentadiene, bromocyclopentadiene, cyclohexadiene-1,3, chlorocyclohexadiene-l,3 and bromocyclohexadiene-1,3. Esters of maleic acid that can be employed in the process of the invention include diallyl maleate, monoallyl maleate, dimethallyl maleate, dicrotyl maleate, and like beta,gammaalkenyl esters of maleic acid having not more than 4 carbon atoms in the beta,gamma-alkenyl group.

As a specific embodiment of the process of the invention a cyclic conjugated diene such as cyclopentadiene may be mixed with an allyl-type ester of maleic acid, e. g. diallyl maleate, and the resulting mixture heated to a temperature of about 100 C. for a reaction time of about 4 hours. The reaction product may then be fractionally distilled in order to obtain the desired 3,6-endoalkylene-1,2,3,G-tetrahydrophthalic acid ester.

The beta,gamma-alkenyl esters of 3,6-endoalkylene-12,3,6-tetrahydrophthalic acids that are produced by the process of the present invention are useful inter alia as plasticizers, as light stabilizers for resins of the vinylidene chloride type, as insecticidal toxicants which may be used per se or in admixture with other substances and, in particular, as intermediates for the preparation of useful polymers, including homopolymers as well as copolymers with such polymerizable ethylenic compounds as styrene, vinyl halides, vinylidene halides, vinyl esters of saturated monocarboxylic acids, methyl acrylate, methyl methacrylate, allyl halides, allyl esters of saturated monocarboxylic acids, vinyl ethers, conjugated butadiene, diallyl phthalate and the like. The polymers and copolymers can be used in the preparation of surface coatings, as molding resins, and as casting resins.

The invention may be illustrated by the following examples wherein the parts are parts by weight.

Example I Diallyl 3,6 endomethylene 1,2,3,6-tetrahydrophthalate was prepared by adding about 2 parts of cyclopentadiene to about 5 parts of diallyl maleate which contained a small amount of a polymerization inhibitor comprising tannic acid. The resulting mixture was heated to a temperaa ture of about C. and maintained at that temperature for about 4 hours. Distillation of the reaction mixture resulted in the separation of an 88% yield of pure diallyl-3,G-endomethylene- 12,3,6-tetrahydrophthalate. Diallyl 3,6-endomethylene-1,2,3,6-tetrahydrophthalate boils at C. to 123 C. at 1.5 mm. Hg pressure. It is a clear liquid which remains water-white even after prolonged periods of standing. Its specific gravity (20/4) is about 1.1145 and its refractive index (20/D) is about 1.4950.

Example II The monoallyl ester of 3,6-endomethylene- 1,2,3,6-tetrahydrophthalic acid may be prepared from cyclopentadiene and monoallyl maleate using substantially the same procedure as is employed for the preparation of the diallyl ester, as set forth in Example I.

We claim as our invention:

1. A method for the production of diallyl-3,6- endoethylene-1,2,3,6-tetrahydrophthalate which comprises heating a mixture comprising diallyl maleate and cyclohexadiene at a reaction temperature of from about 75 C. to about 125 C. to cause said materials to react by addition to form said *diallyl-3,6-endoethylene-l,2,3,6-tetrahydrophthalate.

2. A method for the production of diallyl-3,6- endomethylene 1,2,3,6 tetrahydrophthalate which comprises heating a mixture comprising diallyl maleate and cyclopentadiene at a reaction temperature of from about 75 C. to about 125 C. to cause said materials to react by addition to form said diallyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalate.

3. A process for the production of a beta, gamma-alkenyl ester of a 3,6-endoalkylene- 1,2,3,6-tetrahydrophthalic acid having 1 to 2 carbon atoms in the endoalkylene group, which comprises heating a mixture comprising a cyclic conjugated diene having 5 to 6 carbon atoms per molecule and a beta,gamma-alkenyl ester of maleic acid at a reaction temperature of from about 75 C. to about 125 C. to cause said materials to react by addition to form said beta,gammaalkenyl ester.

RUPERT C. MORRIS. ALVA V. SNIDER. ROBERT M. HOROWITZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,944,731 Diels et al. Jan. 23, 1934 2,221,663 Rothrock Nov. 12, 1940 2,275,034 Moyle Mar. 3, 1942 2,311,261 Staff Feb. 16, 1943 2,359,038 Hopfi et al Sept. 26, 1944 2,409,633 Kropa Oct. 22, 1946 

1. A METHOD FOR THE PRODUCTION OF DIALLY-3,6ENDOETHYLENE-1,2,36-TETRAHYDROPHTHALATE WHICH COMPRISING HEATING A MIXTURE COMPRISING DIALLYL MALEATE AND CYCLOHEXADINE AT A REACTION TEMPERATURE OF FROM ABOUT 75* C. TO ABOUT 125* C. TO CAUSE SAID MATERIALS TO REACT BY ADDITION TO FROM SAID DIALLYL-3,6-ENDOETHYLENE-1,2,3,6-TETRAHYDROPHTHALATE. 